Those look in good condition.
Small holes in the bass panel dust covers can be repaired with sticky tape. Just a small piece to cover the hole.
You might not need the staples when re-fitting the covers. On mine the wooden side cheeks clamp the cover pretty tightly.
Agreed - I didn't use staples re-assembling mine and they are fine.
I would still rebuild the EHT blocks - they reckon the diodes only last around 14 years; PM me if you want Farnell part numbers for diodes, caps and resistors I used with mine. I would recommend sourcing additional beeswax, as you'll be a little short otherwise when refilling. Just cleaning and doing EHT rebuilds on mine made them incredible!
One of my bass panels has 3 or 4 holes similar to yours, and that speaker is definitely down on bass output a little compared to the other. I also have a small arc burn on the other speaker's treble panel - but treble is fine unless I use volume levels simply not possible with kids in the house, and only then with specific tracks
On yours, I would check whether the other speaker has the clamp fitted too - the Quad clamp supposedly affects the sound quality (not heard it myself), and Mr Sheldon recommends a gas discharge device instead. Could be the cause? Otherwise a new bass panel - my logic suggests if doing one you should do all 4, as the coating changes conductivity with age.
My ESLs, even with their slightly uneven bass output, have displaced my SF Concertinos that were in my main system for the last 10 or so years. They simply sound right to my ears.
Richard